Electrical switching apparatus.



PATENTED NOV. 14

W. J. RICHARDS. ELECTRICAL SWITCHING APPARATUS.

APPLICATION FILED NOV. 4. 1904.

4 SHEETS-SHEET 1.

izmewim/ No. 804,844. PATENTED NOV; 14, 1905.

W. J. RICHARDS.

ELECTRICAL SWITCHING APPARATUS.

APPLICATION FILED NOV. 4, 1904.

4 SHEETS-SHBET 2.

Elf Wall E1? J. I: and; mow/5 29052224", 5 %m% p PHgpr g N0- 804,34A.PATENTED NOV. 14, 1905. W. J. RICHARDS.

ELECTRICAL SWITCHING APPARATUS.

APPLICATION FILED NOV. 4, 1904.

4 SHEETS-SHEET 3.

WLFPEEE E1 WJWM EH zz ga WALTER J. RICHARDS, OF MILVAUKEE, WVISOONSIN.

ELECTRICAL SWITCHING APPARATUS.

Specification of Letters Patent.

Patented Nov. 14, 1905 Application filed November 4, 1904. Serial No.231,338.

To a. whom it may concern:

Be it known that I, WALTER J. RICHARDS, a citizen of the United States,residing at Milwaukee, in the county of Milwaukee and State oflVisconsin, have invented a certain new and useful Improvement inElectrical Switching Apparatus, of which the following is a full, clear,concise, and exact description, reference being had to the accompanyingdrawings, forming a part of this specification.

My invention relates to electricalswitching apparatus, and moreparticularly to an automatic rheostat especially adapted for use inconjunction with alternating-current motors.

A well-known type of alternating-current motors comprises a primarywinding traversed by multiphase alternating currents, whereby inducedcurrents are set up in a secondary winding or circuit, the reactionsbetween the two circuits serving to produce the torque orrotative'effect in the motor. It is desirable to'control thestarting-current supplied by such motors by means of current-restrictingmeans associated with the secondary winding.

A preferred embodiment of my invention consists of such a motor havingresistances normally included in the secondary circuit,

the resistances being provided with short-circuiting switches controlledby a slow-acting electromagnetic device, through which the circuit isclosed upon the closure of the primary circuit, whereby the resistancein the secondary circuit is gradually cut out as the motor comes up toits normal speed, when the resistances, being completelyshort-circuited, no longer entail a loss of energy which would otherwiseensue.

My invention will be better understood by reference to the accompanyingdrawings, in which- Figure 1 is a diagrammatic view showing theelectrical connections employed. Fig. 2 is a front elevation of theelectromagnetic switching device which forms the subject of the presentinvention. Fig. 3 is a side view of the same, parts being shown incross-section for purposes of clearer illustration; and

connected by means of the main switch 15. The secondary circuit of themotor is illustrated in the form of the star-connected windings 16, 17,and 18, the free terminals of these windings being connected,respectively, with the free terminals of the resistances 19, 20, and 21,resistances and windings being connected at their neutral points, asshown. The electromagnetic switching device serves gradually after theclosure of the motor-circuit to cut the resistances 19, 20, and 21 outof the secondary circuit of the motor.

I shall first explain the mechanical construction of the electromagneticdevice by reference to Figs. 2, 3, and 4 and then explain its operationin connection with the motor by reference to Fig. 1, upon which theparts of the electromagnetic switching device are provided with the samereference characters as those upon the other figures.

At 22 I have shown the base-plate carrying the standards 23, in whichthe shaft 24 is mounted, the shaft being preferably insulated, as shown.Upon the shaft is pivoted a swinging frame 25. This frame when in itslower position extends into a suitable depression 26, formed in thebase-plate. The frame carries a contact-plate 27 and at one end anauxiliary contact-plate 28, insulated from the main contact-plate 27.Above the contactplates carried upon the frame 25 there are a number ofcontact-fingers 31 to 38, inclusive. Each contact-finger is providedwith an adjustable stop in the form of a screw 39 and a locknut 40,these screws resting upon an ordinary rubber strip 41, supported uponthe baseplate. The screws are so adjusted that the three contact-fingers31, 32, and 33 normally rest in a position somewhat lower than that ofany of the other contact-fingers. The next three, 34, 35, and 36, areadjusted to an intermediate position, while the two contact-fingers 37and 38 are so adjusted that they will be higher than any of the othercontact-fingers. Each contact-finger is provided with a spring 42, eachspring opposing the upward motion of the associated contact-finger. Thecontact-fingers are insulated from each other and from the shaft 24,about which they may rotate, and each contact-finger is provided with asuitable binding-post 43, to which the contact-finger is connected bymeans of the pigtail 44. In Fig. 4 certain of the springs 42 are brokenaway to illustrate the electrical connection with the contact fingers.The movement of the frame 25 and its contactplates 27 and 28 is causedby means of a solenoid 4 1, the solenoid being placed within thelaminated iron field-magnet 15, the lamina of this magnet being held inposition by means of the side plates 16 and 47, the rivets 18 serving toclamp the side plates together. These side plates at their lower endsare provided with suitable feet 19, by means of which they are securedto the base-plate by the cap-bolts 50. Alaminated plunger or core 51 ismounted within the field-magnet and solenoid, the lamina of the plungerbeing held together and in position by means of the side plates 52, therivets 53 serving to hold the side plates together. The side platesextending downwardly form a forked end within which the tongue 54 of theframe 25 is pivoted by means of the pin 55, these two members beingpreferably insulated from each other, as shown. At the upper end thecore 51 is pivoted upon a forked lever 56 by means of the pin 57, thelever being adapted for oscillation about the pin 58, which is carriedin suitable projections of the side plates 16 and 17. At its free endthe lever 56 is .pivoted, by means of the pin 59, to the end of apiston-rod 60, to which the piston 61 is attached, this piston, with thecylinder 62, constituting a dash-pot which retards the upward motion ofthe core 51 when attracted on account of the energization of thefield-magnet, within which it is mounted. The piston has a valve-plate60 loosely held thereon by headed pins 61. Upon downward stroke of thepiston this plate covers the large opening 62 through the piston andrestricts the flow of air to the fine opening 63 and the motion of thepiston is retarded. Upon upward motion, however, the valveplate exposesthe large opening and the retarding effect is removed. Theretractingspring 63 is connected at its upper end to the lever 56 and atits lower end to an extension 6 1 of the side plate 17, this extensionserving also as a point of attachment for the lower end of the cylinder62, the connection being made by means of the pin 65, which permits theoscillation of the cylinder required on account of the movement of thelever 56 about its fulcrum at 58.

As will appear from reference to the diagrammatic drawing of Fig. 1, theclosure of the main switch 15 causes the closure of a circuit throughthe solenoid 14, whereby the magnetization of the field-magnet causes anupward attraction of the core 51, bringing the contact-plate 27 firstinto engagement with the three contacts 31, 32, and 33, and as thesecontacts are connected with points intermediate to the terminals of theresistances 19, 20, and 21 the inner portions of the resistances areshort-circuited or cut out of the secondary circuit of the motor. Thedash-pot serves to retard the upward motion of the core; but within ashort time the contact-plate 27 is brought into engagement with thecontact-fingers 34, 35, and 36, wereby the re maining portions of theresistances are shortcircuited out, thereby leaving the secondarywindings of the alternating-current motor alone in the secondarycircuit, except for the extremely low resistance of the contact-lingersof the switching device and the conductors leading to them.

Connected with the motor M, I have shown an air-compressor U, whichsupplies compressed air to the pressure system,represented by the tank Tand the pipe P, leading therefrom to suitable pneumatic appliances. (Notshown.) The suction-Valves of the pump, as in my copending application,Serial No. 202,567, are retained normally in an open or unseatedcondition, due to the weight of the cores and 70. Thus during theinitial supply of current to the motor there is no load upon thecompressor; but as the contact-plate 28 comes into engagement with thecontact-fingers 37 and 38 a circuit is closed from the main 11, throughcontact-linger 38, contactplate 28, contact-finger 37 to solenoids 71and 71, and thence to the main 12. The energization of the solenoids 71and 71 causing the upward attraction of their cores 70 and 7 0,respectively, removes the pressure of the levers 72 and 72 from thestems of the suction-valves, thereby permitting the valves to seatthemselves and upon the continued operation of the compressor will causethe delivery of air through the discharge-valves into the reservoir T.\Vhen the motor-circuit is opened by means of the main switch 15, thesolenoids 71 and 71' are deenergized, whereupon the weight of theircores 70 and 70 causes the suction-valves to be lifted from their seats.The deenergization of the solenoid 14; permits the return of the core 51to its normal position, the downward movement of the core beingmoderated by the tension of the spring 63. As the contact-plates 27 and28 return to their lower or normal position the electrical connectionswith the contact fingers are broken, thereby establishing the effectiveconnection of the resistances 19, 20, and 21 with the secondary windingsof the motor. The motor of'course comes to rest when its circuit isbroken, where it will remain until the main circuit is again closed andthe above-described operationswill be repeated.

While I have shown and explained one means of employing my presentinvention, 1 do not wish to be limited to its use for this purpose only,nor do I wish to limit myself to the precise construction set forth.

The principle and scope of my invention are indicated in the followingclaims:

1. In a device of the class described, the combination with a pluralityof pivoted contact-fingers, of an adjustable stop for each finger, anoscillating contact-plate, electromagnetic means for causing themovement of said contact-plate, and retarding mechanism serving toretard the movement of said contact-plate upon energization of saidelectromagnetic means.

2. In a device of the class described, the combination with a pluralityof pivoted contact-fingers mounted for rotation upon a common axis,adjustable stop mechanism for adj usting the normal position of eachfinger independently of the others,a moving contact-plate adapted forengagement with said fingers, an electromagnet, a' core for said magnetconnected with said contact-plate whereby the plate is moved uponenergization of said magnet, and a dashpot serving to retard themovement of said contact-plate upon energi- Zation of saidelectromagnet.

3. In combination, a plurality of contactfingers independently mountedfor rotation about a common axis, adjustable stop mechanism associatedwith each contact-finger, a spring serving to maintain eachcontact-finger in a normal position, an oscillating contact-platemounted to rotate about the common axis of said contact-fingers, atongue extending from said contact-plate, an electromagnet-coreconnected with said tongue, a C-shaped field-magnet of laminated ironsurrounding said core, a solenoid for said magnet, a lever serving toguide said core in its movements, and a dash-pot associated with saidlever serving to retard the motions of said core.

4:. In combination, a laminated field-magnet 45, side plates 46 and 47,a core 51, a lever 56, a swinging frame 25, pivoted fingers to beengaged by said frame and a dash-pot associated with said lever, allsubstantially as described.

5. In combination, a resistance, a plurality of pivoted contact-fingerselectrically connected with different points in said resistance, stopsfor said contact-fingers, an oscillating contactplate normallyelectrically disconnected from said contact-fingers, and electromagneticmechanism adapted upon energization by an alternating current to bringsaid contact-plate into connection with said fingers.

6. In combination, an alternating-current motor having a secondarycircuit, a fluidpump driven by said motor, an electromagnet controllinga valve of said pump, a resistance in the secondary circuit of themotor, a plurality of pivoted contact-fingers mounted for rotation abouta common axis, stops serving normally to maintain said fingers indifferent positions, electrical connections between difi'erent points insaid resistance and certain of said contact-fingers, a contact-plateadapted to be moved into engagement with the contact-fingers associatedwith said resistance and other contact-fingers connected in a circuitincluding said electromagnet, a second contactplate mechanicallyassociated with the first contact-plate and moving therewith butelectrically disconnected therefrom, and laminated electromagneticmechanism adapted upon energization to cause the movement of saidcontact-plates, whereby the first contactplate engages thecontact-fingers associated with said resistance, and thereafter thesecond contact-plate engages the contact-fingers associated with saidelectromagnet and a retarding device for retarding the movements of saidcontact-plates.

7. In combination, a C-shaped field-magnet of laminated iron, sideplates for said fieldmagnet, an extension formed integrally with one ofthe side plates, a core for said fieldmagnet, an electromagnet-coil forsaid fieldmagnet, a lever pivoted to said core and said side plates,serving to guide said core within the field of the magnet, a springextending between said extension and said lever, a dashpot cylinderpivoted to said extension, and a piston for said dash-pot connected withsaid lever, substantially as described.

8. In combination, a C-shaped field-magnet of laminated iron, sideplates for said fieldmagnet, an extension formed integrally with one ofthe side plates, a core for said fieldmagnet, an electromagnet-coil forsaid fieldmagnet, a lever pivoted to said core and said side platesserving to guide said core within the field of the magnet, a dash-potcylinder pivoted to said extension, and a piston for said dash-potconnected with said lever, substantially as described.

9. In a device of the class described, the combination with a pluralityof pivoted contact-fingers, an oscillating contact-plate,electromagnetic means for causing movement of said contact-plate intoengagement with said contact-fingers, a retarding mechanism serving toretard the movement of said contactplate upon energization of saidelectromagnetic means.

10. In a device of the class described, the combination with a pluralityof contact-fingers pivoted at one end, of a contact-plate pivotedconcentric with said fingers, electromagnetic means for moving saidplate, toward said fingers, and an adjustable stop for each finger fornormally maintaining groups of said fingers at various angles from saidplate, whereby the groups of fingers will be engaged at different times.

11. In a device of the class described, the combination with a pluralityof contact-fingers pivoted at one end, of a contact-plate pivotedconcentric with said fingers, electromagnetic means for moving saidplate toward said fingers, an adjustable stop for each finger fornormally maintaining groups of said fingers at various angles from saidplate, Whereby the groups of fingers will be engaged at different times,and means for retarding the movement of said frame.

12. In a device of the class described, the combination with apivotedcontact-frame, of a plurality of contact-fingers pivoted concentric IIOwith said frame, adjustable means for causing said fingers to assumevarious relative angles When said contact-frame is disengaged therefrom,electromagnetic means for swinging said frame toward saidcontact-fingers, whereby said fingers are successively engaged thereby,stationary terminal posts for said contactfingers, and flexibleconductors connecting said posts with said fingers.

13. In a device of the class described, the combination with a pivotedcontact-frame, of a plurality of contact-fingers pivoted concentric withsaid frame, adjustable means for causing said fingers to assume variousrelative angles when said contact-frame is disengaged therefrom,electromagnetic means for swinging said frame toward saidcontact-fingers whereby said fingers are successively engaged thereby,stationary terminal posts for said contact-fingers, flexible conductorsconnecting said posts with said fingers, and springs secured to saidposts and engaging said fingers for holding said fingers in firmengagement with said contact-frame.

14. In a device of the class described, the combination with a pivotedcontact-frame, of a plurality of contact-fingers insulated from eachother and pivoted concentric with said frame, an adjusting-screw foreach contactfinger, an abutment for each contact-screw, said fingers bymeans of said screws and abutments being adapted to be normally disposedat different angles to each other, electromagnetic means for swingingsaid frame about its pivot into engagement successively with thecontact-fingers, and spring means for normally maintaining saidcontact-fingers against the abutments and for assuring firm electricalcontact thereof with the contact-frame when actuated by saidelectromagnetic mechanism.

15. In a device of the class described, the combination with acontact-frame pivoted at one end to a stationary support, a core ofelectromagnetic mechanism connected with the other end of said frame,contact-fingers insulated from each other and pivoted concentric withsaid frame and adapted to he engaged thereby upon energization of theelectromagnetic mechanism, a field-frame for said electromagneticmechanism, a rigid arm extending from said field-frame, a lever pivotedat an intermediate point to said field-frame, one end of said leverengaging the other end of said core, and dash-pot mechanism connectedwith the other end of said lever and with said rigid arm adapted toretard the motion of said core to bring the contact-frame intoengagement with said fingers. v

16. In a device of the class described, the combination with acontact-frame pivoted at one end to a stationary support, a core ofelectromagnetic mechanism connected with the other end of said frame,contact-fingers insulated from each other and pivoted concentric withsaid frame and adapted to be engaged thereby upon energization of theelectromag netic mechanism, a field-frame for said electromagneticmechanism, a rigid arm extending from said field-frame, a lever pivotedat an intermediate point to said field-frame, one end of said leverengaging the other end of said core, dash-pot mechanism connected withthe other end of said lever and with said rigid arm adapted to retardthe motion of said core to bring the contact-frame into engagement withsaid fingers, and adjusting means for causing groups of said lingers tobe successively engaged by said contact-frame.

In witness whereof I hereunto subscribe my name this 28th day ofOctober, A. D. 190 1.

WALTER J. RICHARDS. l/Vitnesses:

S. H. I-IooLEY, M. O. BLUMENFELD.

